Faculty Publications
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Item A Transformerless Photovoltaic Microinverter using High-gain Z-Source Boost Converter for Single-phase Grid connected Applications(Institute of Electrical and Electronics Engineers Inc., 2020) Prabhu, N.S.; Damodaran, R.; Balasubramanian, B.; Mishra, S.Microinverters are the latest advancements in the area of photovoltaic (PV) technology due to their compact design. They improve energy efficiency of PV systems due to the reduced effect of non-uniform operating conditions caused primarily by shading. However due to the low output voltage rating of PV modules, high output to input voltage gain ratio is required for microinverters integrated to the utility grid. Several of the existing techniques use transformers or coupled inductors to achieve high gain ratios. These often require precise design and increase the size and cost of the PV system. The Z-source network based high-gain converters can offer superior performance with reduced components, size and cost. However their operation in a microinverter for grid connected applications have not yet been studied. Therefore this paper presents a novel microinverter utilizing a high-gain Z-source boost converter followed by an H-bridge inverter. The principle of operation of the microinverter is detailed and the overall gain ratio is obtained. The operating region in the I-V characteristics of PV module is determined and the control strategies implemented are discussed in detail. Simulations are performed in MATLAB/Simulink platform to validate the performance of the proposed microinverter under possible operating condition. © 2020 IEEE.Item A novel AC module with high gain Z-Source converter and pseudo DC-link inverter(Institute of Electrical and Electronics Engineers Inc., 2020) Damodaran, R.; Dastagiri Reddy, B.D.; Balasubramanian, B.The effects of partial shading in low power PV systems can be considerably reduced by using a single PV module of appropriate rating. Such a system is termed as the AC module in the literature and consists of a PV module along with the required power electronic circuitry, known as module integrated converter (MIC). The AC module integrated with the grid is required to operate at high efficiency and provide an output voltage of the expected magnitude and frequency. In this paper an efficient MIC with pseudo DC-link (pDC-l) for grid integration of AC module is proposed. The proposed MIC is claimed to be high efficient due to the fundamental frequency operation of the inverter. To obtain a pDC-l of required magnitude from single photovoltaic (PV) module, a high gain Z-source buck-boost converter (ZBBC) is used. It is followed by an unfolding circuit which operates at fundamental frequency to convert the pDC-l to sinusoidal output. The fundamental frequency operation reduces the switching losses without affecting the total harmonic distortion (THD). The operation of the ZBBC, when used to obtain a pDC-l output is analysed and a simple closed loop control is developed. The control ensures a pseudo DC-link voltage at the input of the H-bridge that acts as an unfolding circuit. The control also ensures power balance by controlling the current injected to the grid. Simulations of the proposed AC module with ZBBC cascaded with pDC-l inverter have been carried out using MATLAB/Simulink platform and the results are presented to validate the proposed MIC and its closed loop control. © 2020 IEEE.Item Effect of Partial Shading on PV Fed Induction Motor Water Pumping Systems(Institute of Electrical and Electronics Engineers Inc., 2019) Mudlapur, M.; Ramana, V.V.; Damodaran, R.; Balasubramanian, B.; Mishra, S.Partial shading is one of the certain conditions in photovoltaic (PV) power plants. Often the panels get partially shaded due to soiling, clouds, and trees. The effect of shading is of high concern and importance especially in applications such as water pumps due to agricultural environments in which they are employed in. However, the research focus on PV fed pumps till date has been restricted to only uniform shading conditions. Unlike uniform shading conditions during maximum power tracking, where the panel voltage remains almost constant for an entire range of irradiance, partial shading offer conditions such as highly variable panel voltage and transitions of intermediate DC-DC power converter from continuous conduction mode to discontinuous conduction mode. These effects severely affect the performance of the power converter and, therefore, the power output of the pump. This paper presents a study on the effects caused by partial shading conditions on pumps through simulations and verified by experimentations. The simulation and experimental results are found to be in good agreement with each other. This research thus helps in understanding the detrimental effects caused by partial shading conditions and thus serves as a reference tool for practitioners who wish to study PV fed pumps. © 1986-2012 IEEE.Item Modified Current Control for Tracking Global Peak Under Fast Changing Partial Shading Conditions(Institute of Electrical and Electronics Engineers Inc., 2022) P, P.; Vignesh Kumar, V.; Balasubramanian, B.; Ramana, V.The power - voltage (P-V) characteristics of photovoltaic (PV) systems exhibit multiple power peaks under partially shaded conditions. Several global maximum power point tracking (GMPPT) algorithms in the literature recognize the irradiance change, only after the convergence of operating point to global peak, or use additional hardware to call GMPPT subroutine at definite time intervals to detect any insolation change, and thus track the global peak. However, during fast changing partial shading conditions, these methods are less effective, as they do not detect any irradiance change during the tracking phase of any shading pattern. This paper proposes a novel modified current control approach that uses current as a parameter to detect the insolation change during the tracking phase and track the global peak under fast changing partial shading conditions without any additional hardware. The proposed technique improves the tracking efficiency by as much as 39%, thus proving to be effective under fast-changing partial shading conditions. The superior tracking performance of the proposed algorithm over the existing techniques in terms of its tracking efficiency, dynamic tracking capability, tracking speed, and convergence to the global peak is demonstrated with extensive simulations using MATLAB/Simulink and experimental results. © 1986-2012 IEEE.Item A Novel Algorithm Based on Voltage and Current Perturbation to Track Global Peak Under Partial Shading Conditions(Institute of Electrical and Electronics Engineers Inc., 2022) P, P.; Vignesh Kumar, V.; Koothu Kesavan, K.K.; Balasubramanian, B.Under partial shading conditions, photovoltaic (PV) systems exhibit multiple peaks in their power-voltage (P-V) characteristics. It is essential to extract maximum energy from the PV system. The global maximum power point tracking (GMPPT) algorithms presented in the literature, track the global peak using different methods. It is imperative to have minimal convergence time for GMPPT process. This paper proposes a novel algorithm to track the global peak using voltage and current perturbation. The new GMPPT algorithm operates in a current perturbation or voltage perturbation mode, based on the value of a control variable. In either mode, the proposed technique generates reference current or reference voltage, for navigating the operating point to GMPP location. The proposed algorithm is compared with two GMPPT algorithms, namely, modified maximum power trapezium (M-MPT) and high-performance GMPPT algorithms. The simulation studies are performed in MATLAB and is validated using a laboratory prototype, with dSPACE 1202 MicroLabBox controller for implementing GMPPT methods. Simulation and experimental results show that the new technique exhibits superior performance in terms of tracking time. Also, the energy efficiency is improved by 40% while using the proposed GMPPT algorithm for the irradiance profiles considered in this paper compared to the other two techniques. © 1986-2012 IEEE.Item Development of Small Signal Model and Stability Analysis of PV-Grid Integration System for EV Charging Application(Institute of Electrical and Electronics Engineers Inc., 2024) Kanimozhi, K.; Koothu Kesavan, K.K.; Nagendrappa, N.; Balasubramanian, B.In this article, grid interactive photovoltaic (PV) system is designed for an electric vehicle (EV) charging application, and the stability of the system is analyzed. The small signal model for the system is derived by averaging and linearizing the state space equations, and the condition for stable operation of PV-integrated charger system is identified from the transfer functions. The proposed charger system implements a coordinated control between the converters to maintain a power balance between the sources and load. System stability is examined using root-locus plots and in addition, the controller is designed to improve the overall stability and reliability of the system. The proposed method provides a general framework for modeling EV charging systems which also details the importance of deriving the model with multiple energy sources. Further, proposed topology has bidirectional capability, which transfers excess PV power to the grid during off-charging hours. The efficacy of the proposed method is verified using the MATLAB Simulink environment for the different scenarios, i.e., variation in the irradiation and disturbances in the grid voltage. The experimental study is conducted on a 1.5-kW laboratory prototype using a low-cost digital signal processing controller (launchpad TMS320F28027F) and the measured results authenticate the simulation findings. © 2020 IEEE.Item Design and Laboratory Validation of a Grid-Interfaced Totem-Pole PFC Converter With PR Controller and Isolated Phase Modulated Converter for Solar-Powered Next-Gen EV Charging System(China Power Supply Society, 2025) Kanimozhi, K.; Kesavan, P.K.; Nagendrappa, N.; Balasubramanian, B.This paper proposes a stationery reference frame proportional-resonant (PR) controller for current control of grid-tied converters in an EV charger application. Since it is a viable alternative to rotational reference frame PI compensators in AC applications, the PR controller has been adopted for achieving zero steady state error without using any computationally intensive reference frame transformations. In this paper, a method to design the structure of PR controller and its coefficients according to the desired transient behaviour of AC signal amplitude in PFC converter current loop has been proposed. The importance of suggested PR controller design method is that the grid current magnitude is varying constantly based on the available PV power and battery charger levels which necessitates the controller to act in desired transient behaviour. So, by this way the impact of variation in system parameters have been completely overcome by operating the converter controllers appropriately in a solar powered EV charger system. To verify the effectiveness of the proposed controller design, extensive simulations and experimental studies are performed in a 1.5 kW EV charger system under various PV irradiances and charger power levels. The experimental results obtained from the laboratory prototype confirms the simulation findings. © 2025 China Power Supply Society. All rights reserved.Item Implementation of Coordinated Control and Power Flow Management Strategy for a Solar Powered EV Charging System(Institute of Electrical and Electronics Engineers Inc., 2025) Kanimozhi, K.; Koothu Kesavan, P.; Nagendrappa, N.; Balasubramanian, B.This paper introduces a novel coordinated control and power flow management strategy (CC-PFMS) for a solar integrated electric vehicle (EV) charging system. The CC-PFMS is designed to have inherent power balance capability under various operating modes with multiple energy resources. Further, it will facilitate the direction of power flow from grid to battery or vice versa irrespective of the charger system dynamics. The main advantage of proposed strategy is to identify different conditions such as change in solar irradiance, vehicle availability and battery charging/discharging state and ensure the stable operation. The veracity of the new approach is tested on 1.5 kW charger system having photovoltaic (PV) source integrated with utility grid. The performance of CC-PFMS under various operating modes viz. grid to vehicle (G2V), vehicle to grid (V2G), PV to vehicle (PV2V), PV to grid (PV2G), G2V+PV2V, V2G+PV2G and PV2V+PV2G is substantiated through extensive MATLAB simulations. The experiments were also performed in the laboratory prototype to confirm the simulation findings and recorded results were presented. © 1975-2011 IEEE.